The geometry of the ionic channel lumen formed by alpha-latroinsectotoxin from black widow spider venom in the bilayer lipid membranes

摘要

The dependence of single channel conductance formed by a-latroinsectotoxin (a-LIT) from black widow spider venom in the planar phospholipid membrane on the hydrodynamic radii of different nonelectrolytes allowed to determine the geometry of a-LIT water lumen. It was found that the cis- and trans-entrances of alpha-LIT channel had the same effective radii of 0.55-0.58 nm. Relatively small conductance of alpha-LIT channel (23.5 + 3.7 pS) in a symmetrical membrane bathing solution of 100 mM KCl (pH 7.4) may result from the constriction inside the channel with apparent radius of 0.37 nm located 32.5% of channel length away from the cis-entrance. (c) 2007 Elsevier B.V. All rights reserved.